1. Field of the Invention
The present invention relates to a stereoscopic video signal converting apparatus which is applicable to a stereoscopic television system.
2. Description of the Prior Art
As a conventional stereoscopic video signal converting apparatus, two types of systems are known in the art.
In a first type system, a parallel processing system, left and right video signals, which respectively correspond to video signals of a picture to be seen by left and right eyes, are separately converted into digital signals by an A/D converter. The digital signals thus converted are then separately stored in separated field memories. The video signals stored in the field memories are separately read out. The video signals read out are converted into analog signals by an D/A converter and then the analog signals are derived therefrom as the signals for stereoscopic display. This parallel processing system has an advantage that it can obtain a high degree of picture quality, because it employs full band components of the video signals and therefore there is no drop-out of the video signals. Such a prior art system is disclosed in FIGS. 3 and 11 of U.S. Pat. No. 4,562,463, which is incorporated by reference into this specification.
In a second type system, a sequential processing system, left and right video signals are time-division multiplexed by alternately switching the left and right video signals at every field. The video signals thus time-division multiplexed are converted sequentially into digital signals by an A/D converter and then the digital signals are stored in field memories. The video signals stored in the field memories are read out and then converted into analog signals by a D/A converter. The analog signals are derived therefrom as the signal permitting stereoscopic display. A picture quality of the second type system is degraded with regard to vertical and motion resolutions in comparison with those of the first type system due to partial drop-out in each field of the left and right video signals. However, the second type system has advantage that it can be constructed of one train of a video transmission system, a VTR, a video switcher and a video editor. This is because the video signals are multiplexed in one channel, and multiplexing by field switching is simple and economically arranged. Such a prior art system is disclosed in FIGS. 2 and 12 of U.S. Pat. No. 4,562,463.
However, the above-described two systems are less flexible, since each of the systems is limited in use. That is, one of the systems must be used if picture quality is required, whereas the other system must be used if simplification of transmission is required.